En-ring

• An object for any open subset U of Rⁿ homeomorphic to an n-disk.
• A multiplication map:
• :

Examples

• An -algebra in vector spaces over a field is a unital associative algebra if n=1, and a unital commutative associative algebra if n≥2.
• An -algebra in categories is a monoidal category if n=1, a braided monoidal category if n=2, and a symmetric monoidal category if n≥3.
• If Λ is a commutative ring, then defines an -algebra in the infinity category of chain complexes of -modules.